Single-crystal growth, structure and thermal transport properties of the metallic antiferromagnet Zintl-phase β-EuIn2As2

Abstract

Zintl-phase materials have attracted significant research interest owing to the interplay of magnetism and strong spin–orbit coupling, providing a prominent material platform for axion electrodynamics. Here, we report the single-crystal growth, structure, magnetic and electrical/thermal transport properties of the antiferromagnet layer Zintl-phase compound β-EuIn₂As₂. Importantly, the new layered structure of β-EuIn₂As₂, in rhombohedral (Rm) symmetry, contains triangular layers of Eu²⁺ ions. The in-plane resistivity ρ(H, T) measurements reveal metal behavior with an antiferromagnetic (AFM) transition (T_N ∼ 23.5 K), which is consistent with the heat capacity C_p(H, T) and magnetic susceptibility χ(H, T) measurements. Negative MR was observed in the temperature range from 2 K to 20 K with a maximum MR ratio of 0.06. Unique 4f⁷J = S = 7/2 Eu²⁺ spins were supposed magnetically order along the c-axis. The Seebeck coefficient shows a maximum thermopower |S_max| of about 40 μV K⁻¹. The kink around 23 K in the Seebeck coefficient originates from the effect of the antiferromagnetic phase on the electron band structure, while the pronounced thermal conductivity peak at around 10 K is attributed to the phonon–phonon Umklapp scattering. The results suggest that the Eu²⁺ spin arrangement plays an important role in the magnetic, electrical, and thermal transport properties in β-EuIn₂As₂, which might be helpful for future potential technical applications.